1. Field of the Invention
The present invention relates to a storage device employing a replaceable storage medium. More particularly, this invention is concerned with a storage device such as an optical disk drive that employs a replaceable optical disk cartridge and uses a magneto-optical disk stowed in the cartridge.
2. Description of the Related Art
In recent years, the processing ability and processing speed of personal computers have improved, and the capacities of operating systems or application software packages for programs or data have expanded. Under these circumstances, storage devices are required to be compact and low-cost. Moreover, there is an increasing demand for a storage device offering a large storage capacity and a high processing speed.
An optical disk drive has begun to prevail as a storage device capable of meeting the demands for a compact, low cost, large storage capacity, and high processing speed device. An optical disk cartridge having an optical disk stowed in a cartridge is available as an optical disk employed in such an optical disk drive. Along with the prevalence of the optical disk drive employing the optical disk cartridge, there has arisen a demand for resistance to rough handling, stable performance, improved reliability, and reduction in cost.
In the optical disk drive, a stationary optical unit is included for emitting laser light, with which recorded data is read, to an optical disk, and reading and analyzing light reflected from the optical disk. The stationary optical unit is required to be compact. It is necessary to improve the efficiency in incorporating optical elements into the stationary optical. Moreover, the optical elements are required to be reliable.
As mentioned above, the stationary optical unit included in the optical disk drive employing an optical disk cartridge emits laser light with which data recorded on the optical disk is read, and reads and analyzes light reflected from the optical disk. Conventionally, the stationary optical unit is constructed as a unit separate from the body of the optical disk drive. In an effort to meet the recent demand for a compact optical disk drive, an attempt is made to integrate the stationary optical unit into the chassis of the optical disk drive.
For integrating the stationary optical unit into the chassis, a die-cast chassis is used as the chassis, and the stationary optical unit is located on the edge of the chassis. In the stationary optical unit, an outward light path, along which laser light emanating from a light source is propagated to a movable optical system including a carriage that is movable on an optical disk, runs along an extension of a direction of movement of the carriage. A homeward light path, along which light reflected from the optical disk and returned from the movable optical system to the stationary optical unit is split by a beam splitter, and the split laser light is routed to a sensor, runs perpendicular to the outward light path.
When the homeward light path runs perpendicularly to the outward light path in the stationary optical unit, the homeward light path must be isolated from other members of the optical disk drive for fear the members may interfere with the ray axis of the laser. This poses a problem in that the depth of the optical disk increases.
Moreover, if the stationary optical unit is integrated into a die-cast chassis, since the precision in the dimensions of the die-cast chassis is not very high, an auxiliary alignment device must be installed outside the optical disk drive in order to improve the precision in incorporating optical elements into the stationary optical unit. This poses a problem in that man-hours required for incorporating the optical elements into the stationary optical unit increase to raise the cost of the optical disk drive.
Furthermore, a sensor included in the stationary optical unit is locked in a mount using an adhesive. If the adhesion of the adhesive weakens with a rise in ambient temperature, a flexible printed-circuit board having the sensor mounted thereon shifts. This poses a problem in that the reliability of the sensor deteriorates.
Accordingly, an object of the present invention is to provide a compact inexpensive storage device such as an optical disk drive adaptable to high-density optical disks, and capable of solving the disadvantages of a stationary optical unit integrated into a die-cast chassis. Moreover, the storage device makes it possible to reduce the depth of an optical disk drive, decrease man-hours required to incorporate optical elements into the stationary optical unit, and suppress an increase in the cost of the optical disk drive. Furthermore, the storage device helps improve the reliability of a sensor.
For accomplishing the above object, the present invention presents the first to fifth aspects described below.
In the first aspect of the present invention, a storage device has a first light path and a second light path defined therein. Specifically, along the first light path, laser light emanating from a laser light source is passed through a collimator lens and a beam splitter and routed to a movable optical system that accesses an optical storage medium. Along the second light path, light reflected from the optical storage medium and returned from the movable optical system is split into a plurality of rays by a beam splitter, and one of the rays is routed to a sensor via a servo unit and a condenser. The sensor has the abilities to detect information recorded on the optical storage medium, detect the state of laser light converged on the optical storage medium, and detect a track of the optical storage medium to which laser light is irradiated. An angle at which the second light path meets the first light path is 90xc2x0+xcex1 where xcex1 denotes a positive number.
According to the first aspect, the angle at which the second light path meets the first light path is larger than 90xc2x0. Therefore, interference of the second light path with any other component can be avoided, and the overall length of the storage device can be reduced.
In the second aspect of the present invention, the storage device provided from the first aspect has an alignment projection formed on a surface of a servo unit to be disposed on the second light path which is opposed to the second light path. An alignment hole into which the alignment projection is fitted without any gap between them is bored in the bed of the second light path so that the alignment hole will coincide with the alignment projection.
According to the second aspect of the present invention, the man-hours required for disposing the servo unit on the second light path are reduced. This makes it possible to readily manufacture the storage device.
In the third aspect of the present invention, the storage device provided from the first or second aspect has a sensor, which is to be disposed on the second light path, mounted on a flexible printed-circuit board. A sensor-mounted portion of the flexible printed-circuit board is locked in a sensor mount. The other end of the flexible printed-circuit board is coupled to a printed-circuit board placed on the back of the chassis on which the second light path is defined. The sensor mount has a concave part that receives the sensor-mounted portion of the flexible printed-circuit board, and a leading-out groove used to lead the flexible printed-circuit board out of the concave part. A wall against which an end of the sensor-mounted portion of the flexible printed-circuit board abuts is formed on one edge of the concave part. The sensor-mounted portion of the flexible printed-circuit board is locked in the concave part with the end thereof abutting against the wall.
According to the third aspect, the sensor-mounted portion of the flexible printed-circuit board will not be shifted despite a rise in ambient temperature. This leads to improved reliability of the sensor.
In the fourth aspect of the present invention, the storage device provided from the first aspect has the chassis thereof die-cast. A stationary optical unit having the first and second light paths defined therein is formed as an integral part of the die-cast chassis at an end of the chassis.
According to the fourth aspect, the solid-state optical unit is formed as an integral part of the chassis. Consequently, the storage device can be manufactured readily.
In the fifth aspect of the present invention, any of the storage devices provided from the first to fourth aspects has the beam splitter thereof realized with an ordinary beam splitter whose reflecting surface is inclined at 45xc2x0. The beam splitter is turned by xcex1/2xc2x0 with respect to the ray axis of light propagating along the first light path.
According to the fifth aspect, an existing beam splitter can be adopted. This helps suppress an increase in the cost of the storage device.
In the sixth aspect of the present invention, there is provided a chassis of a storage device employing an optical storage medium, whose base is comprised of at least a movable optical unit stowage for installing a movable optical unit which moves across the tracks of the storage medium, and stationary optical unit for emitting a laser light and for receiving a reflected laser light from the movable optical unit, the stationary optical unit comprising: a first groove for forming a first optical path which leads the laser light emitted from a laser light source to the movable optical unit; and a second groove for forming a second optical path which leads the reflected laser light from the movable optical unit to a sensor; wherein an angle at which the second groove meets the first groove is 90xc2x0+xcex1 where xcex1 denotes a positive number.
According to the sixth aspect, a chassis having a stationary optical unit can be formed compact so that the overall length of the optical disk can be minimized.